update comments;
update comment;
Add libvarx/ for variable data without hidden @data alternative of libdatax;
Stream/ become Varx from Datax;
Datax will be child of Varx;
rename module File -> Save to avoid confict;
Save#save, ext_save doesn't take any param;
Remove rescue in Exe#exe()/ It has been difficult to track down the error source. rescue for general error has to be effective only server mode.;